Re: HID Fog light question
Yes you will need some sort of relay harness or anti-flicker module otherwise you will have issues on a 2015. Like Da Jeeper said above, Im more for an LED setup as HID in fogs doesn't really seem like the best way to go for a few reasons....
First off, fog lights go off when you put the high beams on, then back on again with the low beams. Depending on how or where you drive that can be a LOT of re-starts on the HIDs and that is not good for the bulbs, ballasts, or even the wiring. Not only that but HID usually takes a couple seconds to fully warm up. The other issue is all the extra wiring and modules to go along with them would make for a somewhat complicated install.
I say go the LED route like mentioned above. MUCH cleaner, much easier, and they have been proven to produce very good output in the factory housings. If you have a little extra money to burn then without a doubt go with the oem SRT LED fogs. They are amazing!!! I did this to my 2015 High Altitude and did an extensive write up in this forum. If you don't want to go with the more expensive SRT LED fogs, then a quality H11 plug and play will work fine. You will still need the anti-flicker module though.
2015 Jeep Grand Cherokee High Altitude, Bright White, V6, HK audio